The invention relates to a method of vacuum cooling moisture-containing foodstuff articles and includes apparatus for carrying out the method. The invention relates particularly to a method and apparatus for controlling rates of vacuum cooling.
Moisture-containing foodstuff articles can be cooled by subjecting the articles to reduce pressures, such that the moisture in the articles evaporates, the latent heat of evaporation being removed from the articles. In particular, this method can be used to cool baked farinaceous products such as bread and pie crusts. Vacuum cooling of foodstuff articles is attractive because it allows the temperature to be reduced quicker than is possible by the traditional method of simply allowing the articles to cool under atmospheric pressure, and it also ensures that the articles are in a controlled atmosphere during cooling which avoids certain disadvantages (e.g. spore growth) of the traditional atmospheric cooling.
However, it is sometimes difficult to carry out vacuum cooling of foodstuff articles without detracting from the desired characteristics of the finished articles. For example, if the article is of a type which will easily distort, too-rapid cooling will spoil the article, or even cause it to explode, whilst on the other hand if the cooling is too slow, then a thick hard crust may form on the article.
In the Specification of United Kingdom Pat. No. 1,413,481 a method of exercising control over the rate of cooling of farinaceous foodstuff articles by vacuum cooling is described. The present invention provides a method of excercising control over a vacuum cooling process, which may be used in conjunction with the method described in U.K. Patent Specification No. 1,413,481 but it is to be understood that the invention can also be used in instances where the method of that Patent is not employed.